The following types of bearing sets are known to the art. These sets are, for example, mounted within an asynchronous motor, the rotor of which is housed within the main bearings, which are magnetic.
The bearing sets form secondary bearings, also termed gear chassis, which support the shaft in the event the primary bearing malfunctions.
The bearing sets known to the state of the art comprise an element that mounts the two external bushings axially within the chassis, which exerts an axial preload on the external bushings, and which is relatively flexible.
Moreover, the two external bushings are arranged within the chassis so that there is an end-play between them.
A damping element is positioned immediately around the two exterior bushings.
The bearings are ceramic bearing elements.
The bearing set known to the art have the following drawbacks.
When the bearing set undergoes radial stress by the rotor shaft, the coaxial positioning of the two bearings is not ensured, due to the axial end-play between the two external bushings, which in turn is owing to the fact that the external bushings are in direct contact with the damping element, and because of the relatively weak axial preload.
The damping element cannot dampen the shaft's radial displacement without damping the radial displacement of the bearings with respect to the other one within the housing. The angular deviation of the shaft, or the displacement of the shaft around an axis perpendicular to its rotational axis, displaces the bearings with respect to one another.
Thus the concentric arrangement of the bushings is not ensured.
Since the bearings are angular contact bearings, radial stress is translated into a reactive axial force, which acts against the preload force. The preload, therefore, cannot be defined in this case.
Embodiments of the present invention intend to ameliorate these defects and proposes a bearing set that allows dependable functioning when used as a secondary bearing.